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Hi, there is a discussion in some photography forum about monitor brightness, we cannot agree about which screen brightness is recommended.
Someone claims that 80-120 cd/m2 are ideal. For a long time I have been working with 250-275 cm/m2. Now I see that that was probably way too bright. At the moment I have 175 at daylight (no direkt sunlight) and 120 at night with some artificial light. While I can imagine that one can get used to 120 at daylight/direct sun, I cannot believe that that is an optimal setting for daylight since the images look like prints that are viewed at very little light (almost dark grey). I am also wondering whether my Spyder5 measures brightness incorrectly. Accoring to my screens manual my screen only has 250 cd/m2, but according to the Spyder in the center it has even more that 300 cd/m2. I have not had any problems with printing services so far. well, sometimes the result was a little bit too dark.
Which brightness is really recommended now?
Thanks in advance
b
ISO 3664:2000 standard establishes whitepoint brightness level between 80 and 120 cd/m2 or, best, set to the same level as white paper sheet put into viewing booth (1800 lux, D50 lighting) near the monitor. This setting is really useful for prepress operations in digital darkroom conditions. Also the essential condition set by standard is complete isolation from daylight and ambient illumination level near 80 lux. In case of that lighting conditions virtually any brightness level more than 120 cd is over the pain threshold for human eyes. 🙂
The second rule is to get the optimal contrast ratio. ICC standard default is 287:1 but the more it is the better is your perception of image. With a contemporary display naive black level near 0.2 cd/m2 you can get this easy. Typical is 1:300 – 1:600. On the other hand, mention that typical printed contrast ratio is no more than 100:1, and sufficient ratio for full-contrast perception is 64:1.
For daylit room 140-160 cd/m2 used to be an optimal brightness level. Best if it is slightly more brighter than the paper sheet put in front of the display. Note that it is never recommended to work at direct sun.
Thanks Nik, that was really helpful. So at daylight it is actually more than 120 cd/m2, as I suspected. 80-120 only applies for complete isolation form daylight.
One more question: How much are 80 or 1800 lux? I imagine that 80 are very little light, like a small lamp or so? On the other hand, I think that daylight is always several thousands of lux, right? E.g. my window looks to the west, weather is very sunny, I am in in Central Europe, the sun is in the south at the moment, so acutally it is relatively dark in the room, but I think this is still at least 2000 lux, isn’t it?
You may be right. There is a Wikipedia article on Lux.
80 lux is a typical bathroom lighting intensity. ISO 12646 (prepress and digital publishing) requires to get no more than 32 lux (40 w halogen bulb from 2 m). 2000 lux is an average overcast sky daylight or afternoon skylight intensity (and the same for prepress viewing booth).
My own measurements (i1 Pro) of direct sunlight in the morning at 11 a.m. are about 35000 lux and 5400K, ambient lighting in the sunlit room at 1 metre from the window is ~900 lux, and I have 220 lux in front of the display placed round the corner from the window under direct sunlight and 100 cd/m2 of display brightness is comfortable enough to me for that conditions. In afternoon at sunny weather with bright sky, the light in front of the window is 2000 lux (skylight with no direct sun), and full light flow outdoor (sum or skylight and reflected from ground and neighborhood) is near 3000 lux, 100 lux in the middle of the room and 32 lux in front of the display. I’m in Vladivostok, Russia but the longitude (43°11′ N) is the same as for French Riviera, Cannes etc.
In the night time I use 4000 K LED ceiling light so that is about 40 lux near the display, and display brighntess level of 80 cd.
ISO 3664:2000 standard establishes whitepoint brightness level between 80 and 120 cd/m2 or, best, set to the same level as white paper sheet put into viewing booth (1800 lux, D50 lighting) near the monitor. This setting is really useful for prepress operations in digital darkroom conditions. Also the essential condition set by standard is complete isolation from daylight and ambient illumination level near 80 lux. In case of that lighting conditions virtually any brightness level more than 120 cd is over the pain threshold for human eyes. ?
The second rule is to get the optimal contrast ratio. ICC standard default is 287:1 but the more it is the better is your perception of image. With a contemporary display naive black level near 0.2 cd/m2 you can get this easy. Typical is 1:300 – 1:600. On the other hand, mention that typical printed contrast ratio is no more than 100:1, and sufficient ratio for full-contrast perception is 64:1.
For daylit room 140-160 cd/m2 used to be an optimal brightness level. Best if it is slightly more brighter than the paper sheet put in front of the display. Note that it is never recommended to work at direct sun.
For paper to screen match you should look in P2 conditions in 3664. Take a look of these 2 conditions : P1 (for example comparison between original artwork vs proofs, the one you were talking about) and P2 (practical appraisal).
Then look in 12646 for monitor configuration (D50 160 cd/m2) and relate that information with P2.That assumes a near perfect diffuse reflection of paper (LUX = PI * cd/m2) so when you enable softproof in some application like photoshop you get a paper tint to printer profile white (if paper is under the same illuminant as monitor’s white point) and L* drop.
So with a booth in P2 conditions:
- 500lux D50 booth => 160cd/m2 D50 monitor (12646) and rely in softproof for paper color & contrast match to whatever printer/lab profile you are using
- 500lux D50 booth => Start using 160cd/m2 D50 monitor and do to a visual match of white and contrast.
- 500lux D50 booth => Measure and calibrate to that.
First one usually works very well with minor adjustments to lux in booth, also it should not need different calibrations for different papers.
I measured the light in my office now with Displaycal/Spyder5 too. In the afternoon I get similar values as you I think, around 35 lux with almost closed blinds (as the light would fall directly on the screen and the room would heat up even more) close to the window, but only 10-15 close to the screen. Now in the evening it is only 2.5 lux though.
Well, I don’t know. I still find 120 cd/m2 strange at daylight, very dark.
However, recently I took photos of fireworks, and I noticed that I can see the noise in the photos (on the screen) in the evening but not during the day.
Since ambient light is about 5 times stronger during the day than in the evening, does this mean that the screen brightness should be 5 times stronger as well? 20% in the evening and 100% at daylight?
Does Florian actually have an opinion about this problem?
Yes, monitor luminance needs to increase with ambient light level if it can’t be controlled (but I’d strongly recommend the latter if doing color critical work). In ISO 3664 P2 conditions it is mentioned that:
“The level of ambient illumination shall be sufficiently low that the luminance of a perfect reflecting diffuser, placed at the position of the faceplate of the monitor, with the monitor switched off, is not greater than 1/4 of the monitor white point luminance. The level of ambient illumination should be sufficiently low that the luminance of a perfect reflecting diffuser, placed at the position of the faceplate of the monitor, with the monitor switched off, is not greater than 1/8 of the monitor white point luminance.”
Well, I don’t know. I still find 120 cd/m2 strange at daylight, very dark.
It could be several orders of magnitude too low, depending on how strong the daylight is and how the monitor is positioned with regards to windows or other places where daylight enters the room.
However, recently I took photos of fireworks, and I noticed that I can see the noise in the photos (on the screen) in the evening but not during the day.
Viewing glare/flare may also be a problem that contributes to this.
The human eye is an adaptive instrument, and 5 times for correction is about too much 😉 2-3 times is quite enough. Ambient lighting level deviations mostly affect on shadows perception so you have to adjust display black point and/or gamma. 120 cd/m2 is enough for 80-200 lux but is not suitable for daylight in general. Excessive brightness is harmful for eyes and is needed only to provide necessary contrast/dynamic range.
I used to get 5 cd/m2 on my laptop when reading at night but not least as 60 cd/m2 with minimal necessary ambient lighting for correct retinal cone adaptation.
